Class XDouble

Extension methods and other bonus stuff for double.

Inheritance

System.Object

XDouble

Namespace: Galaxon.Core.Numbers

Assembly: Galaxon.Core.dll

Syntax

public static class XDouble : object

Fields

Delta

The default maximum difference between 2 double values being compared for equality.

Declaration

public const double Delta = null

Field Value

Type	Description
System.Double

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MaxExp

The maximum binary exponent supported by the type.

Declaration

public const short MaxExp = null

Field Value

Type	Description
System.Int16

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MinExp

The minimum binary exponent supported by the type.

Declaration

public const short MinExp = null

Field Value

Type	Description
System.Int16

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NumExpBits

The number of bits in the exponent.

Declaration

public const byte NumExpBits = null

Field Value

Type	Description
System.Byte

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NumFracBits

The number of bits in the fraction.

Declaration

public const byte NumFracBits = null

Field Value

Type	Description
System.Byte

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Properties

MaxPosSubnormalValue

The maximum positive subnormal value.

Declaration

public static double MaxPosSubnormalValue { get; }

Property Value

Type	Description
System.Double

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MinPosNormalValue

The minimum positive normal value.

Declaration

public static double MinPosNormalValue { get; }

Property Value

Type	Description
System.Double

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Methods

Assemble(Byte, UInt16, UInt64)

Assemble a new double from parts.

Declaration

public static double Assemble(byte signBit, ushort expBits, ulong fracBits)

Parameters

Type	Name	Description
System.Byte	signBit	The sign bit (1 or 0).
System.UInt16	expBits	The exponent bits.
System.UInt64	fracBits	The fraction bits.

Returns

Type	Description
System.Double	The new double.

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Disassemble(Double)

Disassemble the double into its bitwise components.

Declaration

public static (byte signBit, ushort expBits, ulong fracBits) Disassemble(this double x)

Parameters

Type	Name	Description
System.Double	x

Returns

Type	Description
System.ValueTuple<System.Byte, System.UInt16, System.UInt64>

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FuzzyEquals(Double, Double, Double)

Check if 2 double values are equal for practical purposes.

If two double values differ only by the least significant bit, this is more likely due to inaccuracies in floating point representations than actual inequality.

This code is copied/adapted from Google Guava DoubleMath.fuzzyEquals(). https://github.com/google/guava/blob/master/guava/src/com/google/common/math/DoubleMath.java#L360

I initially tried the algorithm from the Microsoft documentation, it didn't work in all cases. https://learn.microsoft.com/en-us/dotnet/api/system.double.equals?view=net-7.0#system-double-equals(system-double)

Declaration

public static bool FuzzyEquals(this double a, double b, double tolerance = null)

Parameters

Type	Name	Description
System.Double	a	First number.
System.Double	b	Second number.
System.Double	tolerance	The maximum allowable difference between them.

Returns

Type	Description
System.Boolean	If close enough to equal.

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FuzzyEquals(Nullable<Double>, Nullable<Double>, Double)

Compare two nullable doubles for fuzzy equality.

Declaration

public static bool FuzzyEquals(this double? a, double? b, double tolerance = null)

Parameters

Type	Name	Description
System.Nullable<System.Double>	a
System.Nullable<System.Double>	b
System.Double	tolerance

Returns

Type	Description
System.Boolean

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FuzzyIsInteger(Double, Double)

IsInteger() can be a bit strict. This method allows for some fuzziness.

Declaration

public static bool FuzzyIsInteger(double d, double tolerance = null)

Parameters

Type	Name	Description
System.Double	d
System.Double	tolerance

Returns

Type	Description
System.Boolean

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FuzzyIsNegativeInteger(Double, Double)

Check if a double is a negative integer, with some fuzziness.

Declaration

public static bool FuzzyIsNegativeInteger(double d, double tolerance = null)

Parameters

Type	Name	Description
System.Double	d
System.Double	tolerance

Returns

Type	Description
System.Boolean

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FuzzyIsPositiveInteger(Double, Double)

Check if a double is a positive integer, with some fuzziness.

Declaration

public static bool FuzzyIsPositiveInteger(double d, double tolerance = null)

Parameters

Type	Name	Description
System.Double	d
System.Double	tolerance

Returns

Type	Description
System.Boolean

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GetRandom()

Get a random double.

Declaration

public static double GetRandom()

Returns

Type	Description
System.Double

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IsNegativeInteger(Double)

Check if a double is a negative integer.

Declaration

public static bool IsNegativeInteger(double d)

Parameters

Type	Name	Description
System.Double	d

Returns

Type	Description
System.Boolean

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IsPerfectSquare(Double)

Check if a value is a perfect square.

Declaration

public static bool IsPerfectSquare(double d)

Parameters

Type	Name	Description
System.Double	d

Returns

Type	Description
System.Boolean

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IsPositiveInteger(Double)

Check if a double is a positive integer.

Declaration

public static bool IsPositiveInteger(double d)

Parameters

Type	Name	Description
System.Double	d

Returns

Type	Description
System.Boolean

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RoundSigFigs(Double, Int32)

Round off a value to a given number of significant figures.

Declaration

public static double RoundSigFigs(double d, int nSigFigs)

Parameters

Type	Name	Description
System.Double	d	The number to round.
System.Int32	nSigFigs	The number of significant figures.

Returns

Type	Description
System.Double	The rounded number.

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